Corvus Multiplexer

The Corvus Multiplexer was first introduced in 1980. Designed for use with microcomputers, the Multiplexer can link up to 64 devices utilizing a simple star network.

A Multiplexer, used in conjuction with a Corvus disk drive, becomes the center of a "star." This central node contains hardware that polls up to eight devices in a round-robin fashion. These eight devices may be computers or ''Host'' Multiplexers. With eight Host Multiplexers, up to eight computers may then be connected to each host, thereby creating a two level network with a capacity of 64 devices.

Flat cable, 34-wire ribbon, links the network togeth'er. The maximum distance between a Master and a Host Multiplexer or between a Host Multiplexer and a computer is 50 feet (15 meters). In a two-level network this allows a total distance of 100 feet from the drive.

Master Multiplexer

Host Multiplexers

Figure 1-3. Multiplexer Network

3

General Description CORVUS DEALER SERVICE L 7 Receiving Network Hardware

The OMNINET Disk Server,Utility Server, and Multiplexer should all be carefully unpacked and checked for shipping damage. External evidence of rough handling may be symptomatic of damage within the devices.

NOTE:

Any damage claims must be reported to the local office of the shipper so an inspection may be made, and a damage report filed.

If the damaged equipment is a new product, the Corvus Order Processing Department must be contacted for proper return procedures. If the damaged equipment is a recently serviced product being returned under an RMA number (Return Merchandise Authorization number), contact the Corvus Customer Service Department for proper return procedures.

L8 Setting the AC Voltage for the Disk Server and Multiplexer

Be sure the proper line voltage has been selected. To do this look at the bottom right corner on the back of the Multiplexer or Disk Server. There you will find the AC power cord connector and fuse receptacle. Directly underneath the fuse holder, the voltage setting is displayed. If you must change the voltage setting, proceed as follows:

Figure 1-4. CORCOM UNIT

1. Remove the power cord from the CORCOM unit at the rear of the server or Multiplexer.

2. Slide the plastic door to the left, uncovering the fuse.

3. Remove the fuse.

4. Using a pair of needle-nose pliers, remove the voltage selection PCA from just below the fuse holder.

5. Position the voltage selection PCA so that the proper voltage is visible when the PCA is inserted.

6. Insert a new fuse. DO NOT RE-INSERT the fuse you have removed if the voltage setting has been changed.

Proper fuses are:

110-120 VAC 220-240 VAC

lh Amp Slow Blow Fuse

1,4 Amp Slow Blow Fuse 7. Slide the plastic door to the right.

CORVUS DEALER SERVICE General Description L 9 Utility Server Voltage

The Utility Server is manufactured for 100, 110,220, or 240 volts AC. The voltage rating is written on the metallic label on the lUnderneath side of the Server cabinet. If the voltage rating is not compatible with the local voltage, contact your Corvus dealer.

5

CORVUS DEALER SERVICE

2.1 Scope of Chapter

CORVUS DEALER SERVICE

CHAPTER 2

OMNINET INSTALLATION

OMNINET Installation

Installation and operation procedures for the OMNINET are detailed in the OMNINET Installation Guide for each specific microcomputer. This chapter provides an overview of installation procedures.

2.2 Introduction

The Corvus OMNINET Disk Server is enclosed in a beige high-impact, foam-injection cabinet which contains the Disk Server Printed Circuit Assembly (PCA) and the power supply. The power supply, Model HIB5 manufactured by Power One Inc., operates from either 110-120 VAC or 220-240 VAC, SO Hz or 60Hz single phase power. The OMNINET is connected to the disk drive by a 3-foot flat cab~e.

Unshielded twisted-pair wire (Beldon 8205, VWI 20 gauge for trunk and 22 gauge for tap cable) is used for the trunk line and all tap segments to the trunk line. Twisted pair wire must be used as the differential amplifier assumes that there is equal noise on each line. Connections to the trunk line are made utilizing network Tap Boxes. A Molex connector joins the tap line to the Transporter PCA, the network interface within the device.

The combination of a host computer or other network device, a transporter, and a tap cable form a "node." There may be as many as 64 nodes on the network, the OMNINET Disk server being just one of them.

2.3 Trunk l.ine

The layout of the network trunk should be planned keeping in mind these considerations:

1. The maximum trunk segment is 1000 feet (330 meters). When greater lengths are required Corvus Active Junction boxes must be installed at 1000 foot intervals to a maximum trunk length of 4000 feet (1220 meters).

2. The maximum distance between the trunk and the OMNINET device is 15 feet (4.5 meters). When this is not possible, a network 'Long Drop' may be utilized, however, this type of tap increases the trunk length.

~

I

I ^I

~

Figure 2-L Trunk Line

Instructions for creating a trunk may be found in the Installation Guide for the specific microcomputer being used.

6

OMNINET Installation CORVUS DEALER SERVICE

2.4 Tap Boxes

There are three types of Corvus Tap Boxes: Simple Tap Box, Terminator Tap Box, and the Active Junction Box.

Complete installation instructions for each type of box may be found in the Installation Guide for the specific microcomputer being used, or in the Networks Workbook.

2.4.1 Simple Tap Box

A minimum distance of 5 feet (1.5 meters) between Tap Boxes on the trunk is recommended. To make a Simple Drop tap:

1. Using a knife or razor blade, remove about two inches of the trunk cable's insulating jacket, exposing the red and black twisted pair.

2. On the inside back of the Tap Box are two grooved plastic wire guides. Press the black signal wire into the plastic labeled BLACK.

3. Press the red signal wire into the plastic wire guide labeled RED.

4. Insuring that the trunk cable exits the Tap Box in the holes provided, line up the the top cover over the bottom and firmly squeeze the Tap Box Halves together.

figure 2-2. Simple Tap Box

2.4.2 Terminator Tap Box

The network trunk must be terminated at both ends. This is achieved by installing a 100 ohm, 14 watt, ±5% resistor between the black wire and the red wire at each end of the network trunk. To make a Terminator Tap Box:

1. Cut the existing network trunk cable.

2. Using a knife or razor blade, remove about one inch of the trunk cable's insulating jacket, exposing the red and black twisted pair.

3. On the inside back of the Tap Box are two grooved plastic wire guides. Press the black signal wire into the plastic labeled BLACK.

4. Press the red signal wire into the plastic wire guide labeled RED.

CORVUS DEALER SERVICE OMNINET Installation 6. Insuring that the trunk cable exits the Tap Box in the hole provided, line up the top cover over the bottom and

firmly squeeze the Tap Box halves together.

Figure 2-3. Terminator Tap Box

The Terminator Tap Box may also be used to form a node, although it is not recommended when troubleshooting a network.

2.4.3 Active Junction Box

An Active Junction Box is used to achieve a network length of up to 4000 feet (1220 meters). One must be installed for every 1000 feet (330 meters) of network trunk cable from the Disk Server. Active Junction Boxes are also required when a 'T' extension is made on the trunk line. Any such extensions must be terminated.

Installation procedures for an Active Junction Box are:

1. Cut the network trunk cable.

2. Strip the ends of the wires from both segments of the trunk to be connected to the Active Junction Box.

3. Put the red wire from one segment into the left-most tighten down screw marked "+" and its corresponding black wire into the "-" screw right beside it.

4. Put the red wire from the other segment into the right-most tighten down screw marked "+" and its corresponding black wire into the "-" screw right beside it.

s. If the trunk segment wires are shielded, although unshielded wire is recommended, connect the shield to the screw labeled "DRAIN."

6. Next connect the transformer: cu~ a le?gth of network truJ)~ cable q~d str~p both wires at both ends.

7. Paying close attention to polarity: connect the power cable

to

the transformer. Put the red wire from this power cable into the tighten down screw marked "+" at the bottom edge of the Active Junction Box printed circuit board.

8. Put the black wire from this power cable into the tighten down screw marked "-" at the bottom edge of the Active Junction Box printed circuit board.

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OMNINET Installation CORVUS DEALER SERVICE

Transformer

Trunk Trunk

Figure 2-4. Active Junction Box

9. Connect the other end of the red wire to the screw marked 1/+" on the transformer.

10. Connect the other end of the black wire to the screw marked 1/_" on the transformer.

I

11. Check the power connection by plugging the Active Junction box to a 120 volt, 60 Hz wall outlet. The LED on the Active Junction PCB should light immediately.

2.5 Receiving the Disk Server

The OMNINET installation package contains the following items:

L An OMNINET Disk Server with power cord, 2. A three foot (~1 meter) flat ribbon cable, 3. 1 tap cable,

4. 3 Tap Boxes,

5. 2 termination resistors, and 6. A installation manual.

Disk Server

Flat Cable

CORVUS DEALER SERVICE

Resistors Two

Figure 2-5. OMNINET Components The Transporter option package contains the following items:

1. A Transporter card, 2. 1 tap Cable,

3. 1 Tap Box, and

4. An Installation Manual.

Trunk line is purchased as an option in 1000 foot ( ... 330 Meters) lengths.

2.6 Installing the Disk Server

CAUTION:

OMNINET Installation

Power Cord

When Installing or removing an Interface card, the host device must be powered off.

2.6.1 Setting the DIP Switches

Each network device must have a unique "address." This is done by setting the eight microswitches, DIP switches on the OMNINET PCA and the Transporter PCA's.

To set the Disk Server address, open the unit by loosening the two screws located on the back panel that secure the top of the unit, then lift and slide the top cover off the base. On the Disk Server PCA is an 8-microswitch unit, DIP switches. Switches 1 through 6 are used to set the unique OMNINET address in binary representation. The Disk Server must be set to zero. To do this set switches 1 to 6 ON, the switch is pressed down to the ON side.

10

OMNINET Installation

D o

o

CORVUS DEALER SERVICE

o

o

sn~~h---+--+P--f[]

^,11

~~v ^l[][] D~ntDD1 []

ODO[][][]DDD

D~D[][]DD[]DD

o~ ~ [] 0 ^{0 [] [] []o}

II::::::::: ::::::::::

:::::::::::1\

LI

DIDI

o o

Figure 2-6. DIP Switch Location

DIP switch number 7 is used to set a bias offset on the OMNINET trunk cable. It is recommended thatthe Disk Server be used as the network bias device. Therefore, switch 7 should be on for the Disk Server and off for all other network devices. A network bias is used to reduce the effect of noise on the line when it is idle.

The other network devices may be set to any number other than zero. Switch settings for each of the possible 64 device addresses are shown in Table 2-1.

CORVUS DEALER SERVICE OMNINET Installation

Address Switch Setting Address Switch Setting 1 2 3 4 5 6 1 2 3 4 5 6 0

t t t t t t

³²

t t t t t

-1

- t .t t t t

³³

- t t t t

-2

t - t t t t

³⁴

t - t t t

-3

- - t t t t

³⁵

- - t t t

-4

t t - t t t

³⁶

t t - t t

-5

- t - t t ^t

³⁷

- t - t t

-6

t - - t t t

³⁸

t - - t t

-7

- ^- - t t t

³⁹

- - - t t

-8

t t t - t t

⁴⁰

t t t - _t

-9

- t t - t t

⁴¹

- t t ^- t

-10

t - t - t t

⁴²

t - _t - _t

-11

- - t - _{t t}

43

- - _t - _t

-12

t t - - t t

⁴⁴

t t ^{- -} t

-13

- _t - - _{t t}

45

- _t - - _t

-14

t - - - t t

⁴⁶

t - ^{- -} _t

-15

- - - - t t

⁴⁷

- - - - _t

-16

t t t t - t

⁴⁸

t t t t

-17

- _{t i t} - t

⁴⁹

^- t t t

-18

t - _{i t} - t

⁵⁰

t - _{t t}

-19

- - _{t t} - t

⁵¹

- ^- t t

-20

t t - _t - t

⁵²

t t - t

-21

- t ^- t - t

⁵³

- t - t -

-22

t - - t - t

⁵⁴

t ^{- -} t ^-

-23

- ^{- -} t - t

⁵⁵

- - ^- t -

-24

t t t - ^- t

⁵⁶

t t t ^{- -}

-25

- t t - - t

⁵⁷

^- t t ^- -

-26

t - t - - t

⁵⁸

t - t - ^-

-27

- - i - - _t

59

- ^- t

-28

t t - ^{- -} t

60

t t - ^{- -}

-29

- t ^- - - _t

61

- t -

-30

t - - - - t

⁶²

t - - - ^-

-31

- ^{- - - -} t

⁶³

- - ^{- -} -

-1 2 3 4 5 6 1 2 3 4 5 6 Address Switch Setting Address Switch Setting

t =

on

- =

off

Table 2-L Device Address Settings

12

OMNINET Installation CORVUS DEALER SERVICE Switch 8 is not used and should be in the off position for all devices.

2.6.2 Connecting the Cable

Take one end of the three foot flat cable, and connect it to the flat cable connection of the Disk Server PCA. The colored stripe on the flat cable should be to the right when viewed from the back, closest to the three pronged Molex connector.

The flat cable should be installed so that it exits toward the rear of the Disk Server unit. The other end of the flat ribbon is connected to the PROCESSOR Port of the disk drive with the colored stripe to the right as viewed from the back.

Disk Drive

Figure 2-7. OMNINET Cable Connections

To connect the tap line to the Disk Server, locate the three pronged connector on the Disk Server PCA., The two tabs on the tap line connector slip,e over the single back tab of the PCA, and gently lock the tap cable in place.

2.7 Power-On Sequence

The OMNINET Disk Server must be powered up before the disk drive or any host device. If this is not done you must power-off and, again, power-on the server, and then the drive. Following this, computers may then be turned on or off at any time.

CORVUS DEALER SERVICE

CHAPTER 3

OMNINET FUNCTIONAL DESCRIPTION

CORVUS DEALER SERVICE OMNINET Functional Description

CHAPTER 3

OMNINET FUNCTIONAL DESCRIPTION

3.1 Scope of Chapter

This chapter provides an overview of the OMNINET operation. Transporter hardware and commands, and command formats are discussed. The hardware interface is described as are transmission packets and return codes.

3.2 Introduction

A host device issues a command to its Transporter by first formatting a command vector in memory and then sending the address of that vector to the Transporter. The Transporter interprets the command vector and executes the command. There are seven commands which are currently implemented on OMNINET, the two most common of which are the send message command and the setup receive command. Only one message may be sent at a time, but up to four messages may be received without intervention from the host. This is possible because four sockets can be activated by a unique setup receive command vector and as a result, operate completely independently. In addition, all messages for a socket are split into a User Data portion and a User Control portion and each is given its own host memory buffer region by the setup receive command for that socket. Thus, a message destined for a given socket can be routed by the host to any desired place in memory and the user data and control portions of the message can be sent to separate locations.

Additional information may be found in the OMNINET Programmer's Guide, and the User's Guide for the appropriate microcomputer.

3.3 Transporter Hardware

Every host device on the network, microcomputer, disk drive, or Utility Server must have a transporter. In the Corvus Concept, the OMNINET Transporter is built-in. The Disk Server acts as the Transporter for the disk drive. The Utility Server contains the Transporter for peripheral devices such as a printer.

3.3.1 OMNINET Chip Set

The main logic of every transporter is contained in three intergrated circuits called the OMNINET chip set. This set consists of the:

MC6801, MC68A54, and Corvus Monochip.

3.3.Ll MC6801 Microprocessor Chip

The MC6801, U15, is an 8-bit single chip microcomputer unit that contains within it 2048 bytes of ROM and 128 bytes of RAM. The ROM contains the transporter operating code that begins executing at power-up. The RAM is used by the ROM code for storage of command vectors, system variables, and jump tables.

3. 3.L 2 MC68AS4 ADLC Communication Controller

The ADLC (Advanced Data Link Controller), chip U30, provides the interface between the RS-422 transceivers and the rest of the Transporter. The main functions of the ADLC during transmission operations are serialization, zero-insertions, packet framing, CRC generation, and data byte buffering. The ADLC performs these functions in reverse during a receive.

3.3.L3 Corvus Monochip

The Corvus Monochip, chip U16, is a custom designed gate array which provides the timing and control for all data transfers that occur outside the 6801 microcomputer. Due to the slow speed of the serial data transfers of the ADLC compared to the 6801, the monochip must 'freeze' the 6801 and handle all bus synchronization during a DMA transfer.

OMNINET Functional Description CORVUS DEALER SERVICE 3.3.2 RS-422 Transceivers

The transceivers, U5 and U6, are called the driver and receiver. These devices physically connect the OMNINET chip set to the network trunk line.

The driver, IC 75175, accepts data bits from the ADLC and converts them into voltage differentials onto the trunk line.

The arrival of a zero bit from the ADLC causes the 75175 drive to generate a line transition.

The receiver, IC 75174, provides the inverse function of the driver. Line transitions are interpreted as data zeros;

maintained voltage differentials are interpreted as data ones. These bits are sent serially to the ADLC.

3.3.3 Data Bus 7-0

The data bus is an 8-bit, bi-directional, tri-state bus over which message data, command vector addresses, and command information is sent to the transporter section. The transporter uses this bus to send command status and message data to the proceessor and 1/0 sections. The data bus is interfaced to the transporter section through a couple

of latches, 74LS374 at U13 and U14. .

3.3.4 Address Bus 15-0

The address bus is a 16-bit, tri-state bus. The low order 13 bits of the address are latched in the transporter section to be used for DMA transfers. Bits 15-13 of the DMA address are generated by the monochip from information given to it by the 6801. The address lines are interfaced to the transporter section through latches, 74LS374 at U22 and U23.

3.3.5 Key Components and Signals

The key components of the transporter section are installed in sockets. This facilitates troubleshooting procedures and future enhancements. The heart of the transporter is the OMNINET chip set and the RS-422 transceivers.

3.3.5.1 DMA Control lines

Three lines control DMA transfer to and from the processor section dynamic RAM. They are;

DMAREQ This signal is used as a DMA request from the monochip. It is active high.

DMAGQ The Z-80 grants the monochip direct memory access when the signal goes low.

IN lOUT The transporter drives this line high or low depending on whether it is reading or writing.

3.3.5.2 Command Control Lines

A two line handshake controls the command vector address transfer. The signals are;

READ STROBE

This line signifies that the transporter is ready to receive a command vector address byte.

On a low to high transition, the command vector address byte that is present on the data lines is latched into the CAR.

3.4 Command Mechanism

Host devices on the network initiate commands by sending a 24 bit address to the Transporter in the form of 3 bytes. At this address is the command vector which contains a command code, a result record address and other command dependent information.

Before issuing a command, the host must write the value FF hexidecimal to the first byte, called the status byte or return code, of the result record. When the command is completed, the Transporter will signal the host by altering the result record. On host computers that support interrupts, an interrupt will occur after the result record has been modified.

15

CORVUS DEALER SERVICE OMNINET Functional Description Command vector addresses are sent to the Transporter, one byte at a time, using a polling procedure to determine when the Transporter is ready to accept each byte. The status bit of interest is the Transporter READY line, which is an indication of the Transporter's ability to accept the next byte in the sequence, but does not reflect the Transporter's ability to accept the entire sequence immediately. If the Transporter is transferring a message to the host at the beginning of a command sequence, or starts to transfer a message to the host in the middle of a command sequence, the READY line will go low indicating the Transporter's unreadiness to accept the next byte of the command vector address. The READY line will remain low until the Transporter has finished writing its message into the host memory.

CORVUS DEALER SERVICE OMNINET Functional Description Command vector addresses are sent to the Transporter, one byte at a time, using a polling procedure to determine when the Transporter is ready to accept each byte. The status bit of interest is the Transporter READY line, which is an indication of the Transporter's ability to accept the next byte in the sequence, but does not reflect the Transporter's ability to accept the entire sequence immediately. If the Transporter is transferring a message to the host at the beginning of a command sequence, or starts to transfer a message to the host in the middle of a command sequence, the READY line will go low indicating the Transporter's unreadiness to accept the next byte of the command vector address. The READY line will remain low until the Transporter has finished writing its message into the host memory.

Im Dokument The Corvus Service Manual (Seite 16-0)